Snudown is a reddit-specific fork of the Sundown Markdown parser used by GitHub, with Python integration added. In affected versions snudown was found to be vulnerable to denial of service attacks to its reference table implementation. References written in markdown ` [reference_name]: https://www.example.com` are inserted into a hash table which was found to have a weak hash function, meaning that an attacker can reliably generate a large number of collisions for it. This makes the hash table vulnerable to a hash-collision DoS attack, a type of algorithmic complexity attack. Further the hash table allowed for duplicate entries resulting in long retrieval times. Proofs of concept and further discussion of the hash collision issue are discussed on the snudown GHSA(https://github.com/reddit/snudown/security/advisories/GHSA-6gvv-9q92-w5f6). Users are advised to update to version 1.7.0.
Published 2021-10-21 20:15:08
Updated 2023-07-17 15:17:39
Source GitHub, Inc.
View at NVD,   CVE.org
Vulnerability category: Input validationDenial of service

Exploit prediction scoring system (EPSS) score for CVE-2021-41168

0.07%
Probability of exploitation activity in the next 30 days EPSS Score History
~ 29 %
Percentile, the proportion of vulnerabilities that are scored at or less

CVSS scores for CVE-2021-41168

Base Score Base Severity CVSS Vector Exploitability Score Impact Score Score Source First Seen
4.0
MEDIUM AV:N/AC:L/Au:S/C:N/I:N/A:P
8.0
2.9
NIST
6.5
MEDIUM CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
2.8
3.6
NIST
6.5
MEDIUM CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
2.8
3.6
GitHub, Inc.

CWE ids for CVE-2021-41168

  • The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
    Assigned by: security-advisories@github.com (Secondary)
  • The product uses a broken or risky cryptographic algorithm or protocol.
    Assigned by:
    • nvd@nist.gov (Primary)
    • security-advisories@github.com (Secondary)
  • The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources.
    Assigned by: security-advisories@github.com (Secondary)
  • An algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached.
    Assigned by: nvd@nist.gov (Primary)

References for CVE-2021-41168

Products affected by CVE-2021-41168

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